Mooring systems provide a permanent anchorage for a watercraft in a body of water. The system is designed for the watercraft to be attached to it for long periods of time when not in use. A mooring system has an anchor submerged in the body of water and affixed to the bottom. A chain is attached to the anchor and to a buoy. A line from the watercraft to the buoy secures the watercraft to the mooring system.
Mooring anchors are distinguished from conventional anchors, such as kedging anchors, in that conventional anchors are intended to provide temporary anchorages, and therefore are designed to resist lateral forces from one direction but readily disengage from the bottom when subjected to vertical pulls, while mooring anchors are designed to resist lateral forces from any direction as well as vertical forces so as to remain in place at all times.
A mooring anchor should remain engaged with the bottom even when the watercraft attached thereto is subjected to severe forces, such as hurricane winds, even when storm surges increase the local water depth, thereby creating a greater vertical component of pull. Failure to remain engaged results in the mooring dragging, and the watercraft attached thereto may incur severe damage due to collision with other watercraft, rocks, reefs, or the shore.
Current mooring systems use anchors which are either installed or self-seating. Classically, the self-seating anchors used for securing the mooring system have been either large blocks of stone or concrete, which rest on the bottom of the body of water, or mushroom-shaped mooring anchors which partially bury in the bottom of the body of water after a period of time. Blocks rely largely on their weight to prevent the mooring from dragging, and lose much of their effective weight when submerged due to buoyant forces, and consequently must be very massive, making them difficult to transport and install.
Mushroom-shaped anchors, on the other hand, can be smaller as they are intended to bury themselves into the bottom to provide resistance to dragging. However, mushroom anchors are dependent on ideal bottom conditions and need to be tipped on their edges to imbed. Even when tipped on their edges, mushrooms frequently fail to bury adequately. Additionally, the traditional mushroom anchor has a long shank which, when the mushroom is inadequately buried, presents a risk of penetrating the hull or damaging the propeller of the watercraft, particularly when used in waters where the tidal range is large. The long shank also can result in the anchor chain wrapping around the shank, reducing the holding power of the mushroom by shortening the effective length of the chain and thereby increasing the vertical component of force applied to the anchor. Because of the long shank and the hollow mushroom shape of the base, mushroom anchors are frequently fabricated in two parts, with the shank welded to the base. This fabrication complicates the manufacture and can result in the weld rusting out. Extensive damage to watercraft which have been moored with classical mushroom anchors during hurricanes indicates a need for an improved self-seating anchor.
Thus there is a need for a self-seating anchor which can be readily transported and will reliably imbed itself into the bottom under a wide range of bottom conditions, and which does not present a risk of damage to the watercraft when used in areas of large tidal range. There is also a need for an anchor which is readily fabricated by casting.